Cardio Drugs May Prevent Surgery-Linked Heart Attack

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They conclude that in high-risk patients, use of beta blockers can help protect against heart attack during the surgery. The study was less conclusive when it came to patients at lower risk for this kind of complication.

"It is very difficult from our study to conclusively say to low-risk patients that there might not be some harm from use of beta blockers," said senior researcher Dr. Evan M. Benjamin. "At the other end, we are much more confident that we see a benefit in high-risk patients."

The findings are published in the July 28 issue of the New England Journal of Medicine.

More than 20 million Americans each year undergo surgery that does not involve the heart, and about 50,000 of them will have heart attacks as a complication of surgery, the researchers said.

While several major organizations, including the American College of Cardiology, have been recommending use of beta blockers to prevent heart attacks, the evidence for the drugs' beneficial effect is based on "studies that enrolled a small number of patients," according to Benjamin, who is vice president for quality control at Baystate Medical Center, a teaching hospital at Tufts University School of Medicine, in Springfield, Mass.

"Our study tried to answer two questions," he said. "Are physicians following the guidelines for use of beta blockers in non-cardiac surgery? Are beta blockers indeed effective?"

The study looked at records of nearly 783,000 adult patients who underwent major non-cardiac surgeries at 329 U.S. hospitals in 2001 and 2002. Of those, more than 122,000 were given beta blockers during their first two days in the hospital. Benjamin and his colleagues looked at the incidence of heart attacks among those patients.

They found that beta blocker treatment benefited patients at high risk of a heart attack -- patients with two or more cardiovascular risk factors such as preexisting heart disease, diabetes, high blood pressure or high cholesterol levels. In these patients, use of beta blockers reduced the surgical death rate by 12 percent to 42 percent, depending on their number of risk factors.

However, no benefit -- and potential harm -- was seen for healthier patients with less than two cardiovascular risk factors, the researchers noted.

The study does have some flaws, said Dr. Philip J. Devereux, a cardiologist at McMaster University in Hamilton, Ontario. He noted, for example, that there was no information about whether patients were already taking beta blockers for a heart condition at the time of their surgery.

"We don't know why people were given or not given beta blockers," Devereux said. "Hence, it is difficult to know whether beta blockers were responsible for the outcome."

Devereux said he has done a meta-analysis of studies on the use of beta blockers in surgery that is currently pending publication. "The evidence is encouraging, but very weak," he said. "What we need is rigorous evidence from a large-scale, controlled trial."

Benjamin agreed. "The real evidence will come from a [planned] controlled trial, which now is enrolling 10,000 patients," he said.

The trial already has enrolled 4,500 patients in eight countries, said Devereux, who is helping to run it. Such a study is needed because there are potential risks from beta blockers, including a lowered heart rate and increased blood pressure, he said.